I'm using svn:externals to link some libraries stored in one section of the repository to projects that use them.
In marking releases, I mark a release of the library and project that uses it; and then update the project's tag to use the tag URL for the library to make it clear which version of the library is being used.[1]
To make the update, I am copying the lines and updating them to the new location.
I would like to be able to save the original lines as a comment stored in the URL.

While I am using a more recent client (anywhere from 1.4.6 to the latest 1.6.x), the server is SVN 1.4.2 under Apache2/WebDAV.

Is there some way I can turn a line into a comment?

I tried prepending a pound (#) but that didn't seem to work.
I couldn't find anything in the SVN book, or a quick google search.
If this is not supported, I think it would make a good feature to add.

TIA,

Ben

[1] I do understand that SVN can do some of this stuff on its own - that if I check out a tag, it should also check out the dependency at the same revision as the tag, or I could use peg revisions, etc. But I find this approach to be a little cleaner, easier to follow, and more straight forward overall.